The light emission from a scanning tunneling microscope operated on a Ag(111) surface at 6 K is analyzed from low conductances to values approaching the conductance quantum. Optical spectra recorded at sample voltages V reveal emission with photon energies hν>2eV. A model of electrons interacting coherently via a localized plasmon-polariton mode reproduces the experimental data, in particular, the kinks in the spectra at eV and 2eV as well as the scaling of the intensity at low and intermediate conductances.

Rastelli, GianlucaQuantum Coherent Multielectron Processes in an Atomic Scale ContactPeters, Peter-JanRastelli, GianlucaKaasbjerg, Kristeneng2017-10-06T13:58:13ZBerndt, RichardBelzig, WolfgangXu, FeiXu, FeiPeters, Peter-Jan2017-08-10Belzig, WolfgangBerndt, RichardKaasbjerg, Kristen2017-10-06T13:58:13ZThe light emission from a scanning tunneling microscope operated on a Ag(111) surface at 6 K is analyzed from low conductances to values approaching the conductance quantum. Optical spectra recorded at sample voltages V reveal emission with photon energies hν>2eV. A model of electrons interacting coherently via a localized plasmon-polariton mode reproduces the experimental data, in particular, the kinks in the spectra at eV and 2eV as well as the scaling of the intensity at low and intermediate conductances.